During mucosa resection or removal of lesions on or in the wall of certain human and animal anatomy (e.g., gastrointestinal tract, bladder or peritoneal wall) by means of instruments (such as loops, or cutters with or without a cap), lasers, ultrasonic dissectors, etc., bleeding and perforation, for example, of the intestinal or gastric wall can occur. In order to manage these problems, liquid is typically injected under the mucosa into the submucosal layer, resulting in the creation of a “fluid pocket” before removal of lesions (e.g., polyps, adenomas, malignant or benign tumours, endometriosis implants). The primary purpose of this procedural step is to lift off or elevate the mucosal layer or another layer, and hence the lesion, from the muscularis or another layer of the wall. Penetration of the liquid under the mucosa layer causes the mucosa to be “loosened” from the deeper layers by forming a liquid cushion beneath the mucosa. This produces a safety separation or protective surgical margin from the deeper layers as well as providing a protective heat barrier from thermal energy sources.
Traditionally, the liquid injection procedure is done with a needle. These, conventional “needle injection” techniques for delivery of fluidic agents (in order to allow the subsequent removal of selected tissues) have several problems associated with them. One problem associated with these methods is that the user must rely on “tactile feel” and a constant delivery of fluid in order to precisely place the needle within the submucosal layer before additional liquid is injected under the mucosa via the needle. This process is relatively “unselective” and often results in complete perforation of the target tissue and whereas the fluid accumulates under the mucosal layer without integrating with the submucosal tissue matrix, the fluid escapes rapidly (e.g., in less than a few minutes). Additional problems associated with using conventional methods include difficulty in obtaining access to the delivery site (e.g., relative position of the device with respect to the tissue), necessity of repositioning the distal tip of the device in multiple locations, delivering the fluidic agent to the delivery site, accurately injecting the fluidic agent into the appropriate tissue layer or depth within the tissue, and problems maintaining fluid retention within the tissue, etc. In addition, injection of the fluidic agent becomes extremely difficult when the target tissues are moving or are pliable.
Conventionally, once the liquid cushion is formed beneath the mucosa, the mucosal resection is then performed using a snare or cap technique to achieve the operative goals. In the case of larger area tumors, however, a “piecemeal” technique is often employed. Alternatively and potentially more clinically desirable, the mucosa resection can be performed using an “enbloc technique” which is carried out with a flexible needle knife type of electrode. This technique for resection is extremely difficult. In particular, the difficulty of this type of intervention is that the injected liquid leaks out of the “fluid pocket” during the operation, causing the deeper layers to become thermally damaged by the needle knife. This thermal damage can in turn lead to perforation of hollow organs (e.g., intestine) or undesired thermal damage to other tissue layers or structures. In order to avoid perforation for instance, the instrument must be removed several times during the resection procedure and liquid must again be injected under the mucosa.
Accordingly, it is desirable to improve the targeted delivery of therapeutic, diagnostic, or fluidic agents via a tissue selective needle-less fluid introduction process that will facilitate the resection of undesired tissue with increased efficiency.
U.S. Pat. No. 6,752,799 (DE 19 607 922 C2) discloses a medical device and method for the endoscopic injection of a liquid underneath the mucosa. The device disclosed in this patent is spaced a distance away from the target tissue which allows for a thin fluid stream to substantially travel in “free flight” prior to contacting the tissue while the user holds the device at a specific angle. The fluid is introduced in such a thin stream that the hole created in the mucosa closes after itself without allowing an appreciable amount of fluid to escape. The device creates a “fluid pocket” under the mucosal layer. The initial fluid retention issue is addressed using a self sealing micro-hole, however, after the first incision is made, the fluid escapes rapidly. Therefore, continual re-introduction is still required as this device has not improved fluid retention within the tissue.
U.S. Pat. No. 6,126,633 discloses a medical device which is capable of approaching the target region in a safer and easier manner by bending and is used for submucosal needle injection. This addresses the relative position of the device with respect to the target tissue, but however neglects the other major obstacles associated with conventional needle designs.
U.S. Pat. No. 6,666,847 is directed toward providing an improved needle injection system that offers a surgeon easier needle extension and retraction.
Alternative solutions to the problems of bleeding and intestinal perforation are also being tested wherein liquids of different viscosities are used; however, these liquids still leak out of the mucosa. These attempts still do not offer a satisfactory solution because the escape of the liquid out of the submucosa is only slowed, but is not prevented.
Each of these patents discloses devices for submucosal needle injection, however, they fail to address all or the majority of the problems associated with this technically challenging and high risk procedure. For example, these patents do not address the difficulties of “manually” finding the appropriate tissue plane without the risk of complete colonic transection or perforation with a needle device (layer thicknesses range from 0.5 mm to 1.5 mm), the limitations on the device approach to the target tissue, and problems with maintaining fluid retention within the tissue.
It is therefore desired to have a surgical instrument that facilitates the selective introduction of a fluid into tissue layers to allow for elevation and separation of tissue layers. In particular, it is desired to have a surgical instrument that allows the elevation and separation without the requirement for a solid mechanical device insertion or transection through the mucosal layer. In addition, improvements in fluid retention within the target tissue, a device which can approach the tissue at any angle, and/or resection of selected tissues, which will thereby help prevent and avoid damage to surrounding tissues during subsequent procedures are also desired.